How to run a script from a vCenter Alarm action in the VCSA?

As more and more customers transition from the vCenter Server for Windows to the vCenter Server Appliance (VCSA), a question that I get from time to time is how do I run a script using a vCenter Alarm from the VCSA? Traditionally, customers would create and run Windows specific scripts such as a simple batch script or a more powerful Powershell/PowerCLI script. However, since the VCSA is a Linux based operating system, these Windows specific scripts would no longer function, at least out of the box.

There are a couple of options:

If you have quite a few scripts and you prefer not to re-write them to run on the VCSA, then you can instead have them executed on a remote system.

Re-write or create new scripts that would run in the VCSA. You can leverage pyvmomi (vSphere SDK for Python) which is already included in the VCSA. This will allow you to access the vSphere API just like you would with PowerCLI on a vCenter Server for Windows if you had that installed.

Given there are already multiple ways of achieving #1 and I am sure there are other options if you just did a quick Google search, I am going to focus on #2 which will demonstrate how to create a pyvmomi script that can be triggered by a vCenter Alarm action running on the VCSA.

Disclaimer: It is generally recommended that you do not install or run additional tools or scripts on the vCenter Server (Windows or VCSA) itself as it may potentially impact the system. If it is possible, a remote system using programmatic APIs to provide centralize management and configuration is preferred and it also limits the number of users that may have access directly to the vCenter Server.

The following example is based off of a real use case from one of our customers. The requirement was to automatically generate and collect an ESXi performance bundle (part of the support bundle) for all hosts in a given vSphere Cluster when a specific vCenter Alarm is triggered. In this example, we will create a simple vCenter Alarm on our vSphere Cluster that triggers our script when a particular VM is modified as this is probably one of the easiest way to test the alarm itself.

UPDATE (06/14/16) - For generating an ESXI performance support bundle, please have a look at this article which can then be applied to this article in terms of running the script in the VCSA.

When a vCenter Alarm is triggered, there are a bunch of metadata that is passed from the vCenter Alarm itself and stored in a set of VMware specific environmental variables which you can find some more details in the documentation here. These environmental variables can then be accessed and used directly from within the script itself. Here is an example of what the environmental variables looks like for my vCenter Alarm which triggers off of the VM reconfigured event:

The variable that we care about in this particular example is the VMWARE_ALARM_EVENT_COMPUTERESOURCE as this provides us with the name of the vSphere Cluster that we will need to iterate all the ESXi hosts to then generate the ESXi support bundles. I have created the following pyvmomi script called generate_esxi_support_bundle_from_vsphere_cluster.py which you will need to download and upload to your VCSA. The script has been modified so that the credentials are stored in (line 44 and 50) within the script versus prompting for it on the command-line (you can easily tweak it for testing purposes). By default, the script will store the logs under /storage/log but if you wish to place it else where, you can modify line 55.

Note: If you wish to manually test this script before implementing the vCenter Alarm, you will probably want to comment line 105 and manually specify the vSphere Cluster in line 106.

Below are the instructions on configuring the vCenter Alarm and the python script to run:

Step 1 - Upload the generate_esxi_support_bundle_from_vsphere_cluster.py script to your VCSA (I stored it in /root) and set it to an executable by running the following command:

chmod +x generate_esxi_support_bundle_from_vsphere_cluster.py

Step 2 - Create a new vCenter Alarm under a vSphere Cluster which has some ESXi hosts attached. The trigger event will be VM reconfigured and the alarm action will be the path to the script such as /root/generate_esxi_support_bundle_from_vsphere_cluster.py as shown in the screenshot below.

Step 3 - Go ahead and modify the VM to trigger the alarm. I found the easiest way with the least amount of clicks is to just update the VM's annotation 😉 If everything was configured successfully, you should see the vCenter Alarm activate as well as a task to start the log bundle collection. Since the script is being call non-interactively, if you want to see the progress of the script itself, you can login to the VCSA and all details from the script is logged to its own log file in /var/log/vcenter_alarms.log.

Hopefully this gives you an idea of how you might run custom scripts triggered from a vCenter Alarm from within the VCSA. With a bit of vSphere API knowledge and the fact that pyvmomi is installed on the VCSA by default, you can create some pretty powerful workflows triggered from various events using a vCenter Alarm in the VCSA!

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How did you generate the list of environment variables showing the VMWARE_ALARMS_ variables? I’m using a vCenter 6.0 server on Server 2012 R2 and if i run CMD>>SET or Powershell>Get-ChildItem Env: i do not see any VMWARE_ALARM_ variables anywhere, even when i generate an alarm within vCenter. I do see other VMware variables like VMWARE_CFG_DIR but i dont see any _ALARM_ variables at all.

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William Lam is a Staff Solutions Architect working in the VMware Cloud on AWS team within the Cloud Platform Business Unit (CPBU) at VMware. He focuses on Automation, Integration and Operation of the VMware Software Defined Datacenter (SDDC).